What type of sampler is best for obtaining undisturbed samples from soft sediments?

The Shelby tube is specifically designed to obtain undisturbed samples from soft sediments, making it the most suitable choice in this scenario. This sampler consists of a thin-walled steel tube that is sharp-edged and has a relatively small diameter, which minimizes disturbance to the sediment as it is pushed into the ground.

When the Shelby tube is driven into the sediment, it captures a core that retains the natural structure and moisture content of the sediment, essential for accurate analysis of soil properties and behaviors. This is particularly important in geotechnical engineering and environmental studies where understanding the sediment's original condition is critical for assessments and design purposes.

In contrast, other types of samplers like the Split Spoon may disturb the sediment more significantly due to their design and sampling method, while the Modified California sampler does not provide the same level of sample integrity for soft sediments. A sieve is primarily used for separating particles by size and is not designed for obtaining intact samples of sediment. Therefore, the Shelby tube is the preferred option for preserving the original characteristics of soft sediments during sampling.